class MulLayer:
    def __init__(self):
        self.x = None
        self.y = None

    def forward(self,x,y):
        self.x = x 
        self.y = y 
        out = x*y 

        return out 
    
    def backward(self, dout):
        dx = dout * self.y 
        dy = dout * self.x 

        return dx, dy 